This invention relates to the cutting of flexible materials such as fabrics, foam, plastic rubber sheets and the like. In particular, the invention relates to an improved system for spreading material to be cut and then a simultaneous severing of material into multiple patterns having predetermined sizes and shapes.
Cutting systems are typically used to produce from roll goods or sheets pattern pieces which are subsequently assembled into a finished unit. In, for example, the manufacturer of clothing, the same patterns are cut over and over. The pieces are removed from the cutting room and stitched into a completed garment. Through-put has been hampered by the lack of speed in cutting. Moreover, a significant portion of the cost of a finished item is the cost associated with cutting the components. Thus, a standing requirement in the garment and other industries associated with cutting and assembling multiple patterns is to decrease increased costs and yet increase efficiency in the cutting operation.
A variety of techniques have been employed to render more efficient the cutting operation. Generally, speed and efficiency are a function of the spreading of the material onto a cutting surface and the time required to cut patterns from a marker. Prior cutting operations have used power presses and dies in, for example, the cutting of garment patterns wherein standard sizes are replicated many fold. Such die press operations are advantageous in terms of speed but, suffer disadvantages in terms of cost of equipment, rejection rates and system maintenance. Additionally, die systems utilizing presses are not efficient relative to material utilization. The component pieces which form the pattern marker must be spaced at sufficient distances to allow for compensation in ply bending or so-called "valleys" which tend to form as a consequence of the downward force of the cutting die.
Distinct from the die cutting process is the use of knives. These knives may either be sharp thin knives, laser cutters, water-jet cutters and the like. Knife cutting is generally done by remote control having the cutting instrument mounted on a X-Y carriage. The cutting instrument then traces the marker for sequential cutting of the patterns. While such cutting techniques produce quality pieces with low kerf, the rate of cutting is relatively slow vis-a-vis the entire pattern.
By comparison to die techniques wherein simultaneous cutting occurs, cutting rates are deemed to be unacceptably slow. Also, in the case of some cutting devices using heat, multiple layers heretofore could not be cut in the case of synthetic fabrics. The heat associated with cutting bonded the layers together. Thus, only one layer at a time could be cut.
A second deficiency in conventional system is in the spreading of raw material to be cut and in the removal of cut goods from the cutting table. Spreading generally occurs by unrolling from a source under tension one layer of fabric at at time. The fabric is held down on the cutting table either by clamps or vacuum hold-down techniques. The material in either case is therefore stretched such that a degree of distortion exists between the desired pattern size and the pattern cut in the stretched material. In the case of spreading multiple layers, contact between the layer to be spread and the layer already positioned on the cutting table results in interlayer shear tending to crease or wrinkle the layer on the cutting table. Consequently, techiques of spreading material for cutting tend to be slow, labor intensive, and subject the material to distortion if held under tension.
When the material is cut, it is generally removed from the cutting table by means of conveyors or the like where the cut pieces are removed and then reoriented for subsequent stitching. Between the process of removal of the cut pieces intermingling of components results, individual components are sometimes folded and creased and the operation of severing subsequent layers is delayed until all cut pieces have been removed from the cutting table.